U.S. Pat. No. 4,731,921 entitled "Method of Fabricating a Molded Case Circuit Breaker" describes a circuit breaker operating mechanism designed for automated assembly. From a single pole unit, a multi-pole unit is assembled by fastening the required number of the single pole units in a side-by-side modular array. With the increased use of four pole circuit breakers within industrial-rated electric power distribution systems, it is economically advantageous to gang four single pole circuit breakers together and interlock the circuit breakers by means of a handle tie bar assembly.
The use of a tie bar assembly for providing a multi-pole array of single pole circuit breakers is described, for example, in U.S. Pat. No. 4,980,525. The single pole circuit breakers, are ganged together by means of an elongated rivet and are interlocked by means of a handle tie bar to lock the circuit breaker operating handles together and to force them to move together in unison. A hole is formed perpendicular to the vertical extent of each upstanding circuit breaker operating handle and an elongated connecting pin is inserted through the holes of each of the circuit breaker operating handles. A plastic tie bar is then positioned over the operating handles and the interlocking pin to complete the multi-pole assembly.
In the automated assembly of circuit breaker components, it is desirable to assemble the circuit breaker components in a "down-loaded" assembly operation. The down-loaded assembly process facilitates the use of robots at a substantial cost savings. It has been determined however, that the placement of an interlocking pin through the holes in the circuit breaker operating handles in the plane perpendicular to the vertical extent of the upstanding circuit breaker handles, is not easily replicated within an automated assembly process.
As described within U.S. Pat. No. 3,109,899, it is often required to lock a circuit breaker operating handle in its "OFF" position to ensure that the circuit breaker contacts remain open when work is being performed on the associated electrical equipment. The lock described within this Patent comprises a flexible locking clip that is interposed between the operating handle and the associated operating handle slot to prevent the circuit breaker handle from being moved within the slot. The clip can also be used to lock the circuit breaker in the "ON" position to prevent accidental disruption of power flow to critical equipment.
When several single pole circuit breakers are ganged together in the multi-pole array described within the aforementioned U.S. Pat. No. 4,980,525 a separate locking clip must be used with each one of the circuit breaker operating handles to ensure that all of the circuit breaker operating handles remain in their OFF position.
Accordingly, one purpose of this invention is to provide a multi-pole array of circuit breakers utilizing an automatically assembled tie bar assembly which requires a single locking clip to maintain the individual circuit breakers in their ON or OFF position.